The following packet communication device is known. Each line package includes an L2 switch including plural LAN-line accommodation ports and a setting unit mutually connecting ports of the L2 switch. The line package may be connected to another line package using an unused port of the L2 switch as a backup port. When a failure such as a congestion state is detected, a control package changes the setting of the setting unit, so that a failed line package is switched to another line package in which no failure is detected.
Reference may be made to Japanese Laid-open Patent Publication No. 2006-186924.